Researchers examined adherence to infection control policies in more than 1,600 intensive care units at 975 hospitals across the nation.

They focused on three of the most common types of preventable infections in hospitals: central line-associated bloodstream infections; catheter-associated urinary tract infections; and ventilator-associated pneumonia.

About one in 10 hospitals did not have checklists to prevent bloodstream infections, and one in four did not have checklists to prevent ventilator-associated pneumonia. About one-third of hospitals had no policy to prevent catheter-associated urinary tract infections.

"Hospitals aren't following the rules they put in place themselves to keep patients safe," team leader Patricia Stone, a professor of health policy at Columbia University School of Nursing, said in a Columbia news release. "Rules don't keep patients from dying unless they're enforced."

Even when hospitals had checklists, they were followed only about half of the time, the researchers report in the February issue of the American Journal of Infection Control.

Each year in the United States, health care-associated infections cause about 100,000 deaths and lead to about $33 billion in extra medical costs, according to background information with the study.

"Every hospital should see this research as a call to action -- it's just unconscionable that we're not doing every single thing we can, every day, for every patient, to avoid preventable infections," Stone said.

One way that hospitals can improve compliance with infection control rules is to have an electronic monitoring system that tracks if health care workers are following infection control rules. Previous research has shown that these systems reduce infection rates. Only about one-third of the ICUs in the study had this type of system.

Another approach is to have staff who are certified in infection control, but more than one-third of the hospitals in the study did not have a full-time person with such qualifications, the researchers noted.